Stem Cells and Ischemic Brain Injury

干细胞和缺血性脑损伤

• 批准号: 6540367
• 负责人: WALTER C LOW
• 金额: $ 33.41万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6540367
• 关键词: behavior test; brain derived neurotrophic factor; brain injury; cell differentiation; cerebral ischemia /hypoxia; clinical research; fibroblast growth factor; functional ability; green fluorescent proteins; human subject; nervous system disorder therapy; neural plasticity; neurosurgery; neurotrophic factors; nonhuman therapy evaluation; phenotype; spontaneous hypertensive rat; stem cell transplantation; stem cells; stroke; stroke therapy; tissue /cell culture

Studies of bone marrow cells have shown that they can restore neurologic function when transplanted into animals with ischemic brain injury. Recently, our laboratories have isolated a specific multi-potent stem cell population from human bone marrow that is capable of differentiating into neurons, astrocytes, and oligodendroglia in vitro under appropriate culture conditions. We postulate that these bone marrow-derived stem cells can provide an autologous source of donor cells for transplantation and repair in conditions of ischemic brain injury and stroke. In Specific Aim 1 we will determine the neural phenotypes generated from bone marrow-derived human stem cells when transplanted into the brain of spontaneously hypertensive rats. Human stem cells will be transduced to express eGFP to label the donor cells. Bone marrow-derived stem cells will then be transplanted into the striatum, hippocampal formation, or sensorimotor cortex. At various time periods after transplantation, brain tissue from host rats will be studied to identify presence of eGFP labeled cells. eGFP labeled cells will also be examined to determine whether they develop into neurons, glial cells, and/or oligodendroglia. Site-specific differentiation will also be evaluated to determine whether grafted neurons also co-express neurotransmitter markers that are characteristic of neurons that found in the striatum, hippocampus, and cortex. In Specific Aim 2 we will determine the efficacy of transplanted bone-marrow stem cells in ameliorating neurologic deficits associated with ischemic brain injury. The middle cerebral artery will be occluded unilaterally by ligation distal to the branching striatal vessels. This occlusion produces a discrete ischemic lesion of the cortex and results in permanent sensory and motor deficits in the forelimb contralateral to the side of injury. One week after the ischemic event animals will receive transplants of bone marrow-derived stem cells into regions of the neocortex surrounding the area of injury. In preliminary studies we have found that these transplants are capable of ameliorating sensorimotor deficits. The extent of the functional recovery will be assessed over time using a battery of behavioral tests. Also as part of Specific Aim 2 we will determine the time window after ischemic brain injury for stem cell transplantation that will result in an amelioration of neurologic deficits. In these studies ischemic rats will receive transplants at various time periods after ischemic injury and assessed functionally over time using a defined set of sensory and motor tests. In Specific Aim 3 we will investigate possible mechanisms underlying bone marrow-graft induced recovery of neurologic function. Possible mechanisms include trophic effects on neural stem cells of the host brain, the induction of growth factor release by host brain cells, and the reorganization of host fiber connections. The results of these studies will provide information regarding the efficacy of using specific bone marrow-derived stem cells as an autologous source of cells for transplantation in ischemic brain injury, and information regarding possible mechanisms of graft-induced neural plasticity.

对骨髓细胞的研究表明，当用缺血性脑损伤移植到动物中时，它们可以恢复神经系统功能。 最近，我们的实验室已将特定的多功能干细胞种群与人体骨髓分离出来，该干细胞群体能够在适当的培养条件下在体外区分神经元，星形胶质细胞和少突胶质细胞。 我们假设这些骨髓来源的干细胞可以为缺血性脑损伤和中风的供体细胞的自体源来移植和修复。 在特定目标1中，我们将确定当移植到自发性高血压大鼠的大脑中时，由骨髓来源的人干细胞产生的神经表型。 人类干细胞将被转导至表达EGFP以标记供体细胞。 然后将骨髓来源的干细胞移植到纹状体，海马形成或感觉运动皮层中。 在移植后的各个时间段内，将研究来自宿主大鼠的脑组织，以鉴定EGFP标记的细胞的存在。 还将检查具有EGFP标记的细胞，以确定它们是否发展为神经元，神经胶质细胞和/或少突胶质细胞。 还将评估位点特异性分化，以确定移植神经元是否也共表达神经递质标记，这些标记是在纹状体，海马和皮质中发现的神经元的特征。 在特定目标2中，我们将确定移植的骨髓干细胞在与缺血性脑损伤相关的神经系统缺陷方面的功效。 大脑中部动脉将通过与分支纹状体血管远端的连接单侧遮住。 这种闭塞会产生皮质的离散性缺血病变，并导致前肢的永久感觉和运动缺陷与损伤侧面。 缺血性事件发生后的一周，动物将接受骨髓来源的干细胞移植到受伤区域周围的新皮层区域。 在初步研究中，我们发现这些移植能够改善感觉运动缺陷。功能恢复的程度将随着时间的流逝评估，使用一系列行为测试。 同样，作为特定目标2的一部分，我们将确定缺血性脑损伤以进行干细胞移植后的时间窗口，这将导致神经系统缺陷的改善。 在这些研究中，缺血性大鼠将在缺血性损伤后的各个时间段内接受移植，并使用一组定义的感觉和运动测试随时间进行功能评估。 在特定目标3中，我们将研究骨髓移植物诱导的神经系统功能恢复的可能机制。 可能的机制包括对宿主大脑神经干细胞的营养作用，宿主脑细胞释放生长因子的诱导以及宿主纤维连接的重组。 这些研究的结果将提供有关使用特定的骨髓衍生的干细胞作为缺血性脑损伤移植的细胞来源的疗效的信息，以及有关移植物诱导的神经可塑性的可能机制的信息。